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A stationary \( \mathrm{He}^{+} \)ion emitted a photon corresponding to first line of lyman series. The electron liberated from stationary H- atom after this elastic collision will have certain de Broglie wave length \( (\lambda) . \lambda \) will be expressed as \( (0.26 \times \mathrm{x}) Å \) for photo electron Take \( \sqrt{5.51}=2.34 \). The value of \( \mathrm{x} \) will be
ChemistryStructure of AtomJEE Main
Solution:
1656 Upvotes Verified Answer
The correct answer is: 9
Photon emitted from  He + = - 13.6 2 2 1 2 2 - 1
                                            40.8 eV
Liberated electron energy = 40.8 - 13.6
∵  IE of H atom = 13.6 eV
i.e. as if accelerated by electric potential of 27.2 volts .
λ  in  Å  for photo electron = 1 5 0 27.2 = 5.51 = 2.34
2.34 = 0.26 × x             ∴  x = 9

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